The CAS Registry Mumber 84142-53-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,1,4 and 2 respectively; the second part has 2 digits, 5 and 3 respectively. Calculate Digit Verification of CAS Registry Number 84142-53: (7*8)+(6*4)+(5*1)+(4*4)+(3*2)+(2*5)+(1*3)=120 120 % 10 = 0 So 84142-53-0 is a valid CAS Registry Number.